It is generally known in the art of internal combustion engine design to use charge motion control valves in an intake manifold. The “charge” is understood to mean the air-fuel mixture being delivered to the combustion chamber. “Charge motion” is a purposely induced, preferential movement of the charge for more efficient burning in the combustion chamber. There are basically two main types of induced charge motion: tumble and swirl. “Tumble” is understood to mean air turbulence about an axis perpendicular to the longitudinal axis of the cylinder. “Swirl” is air turbulence rotating about an axis generally parallel to the cylinder axis. Today's prevalent method for inducing tumble and/or swirl in an engine is through the use of valves that are configured to preferentially direct air flow through the intake runners and/or combustion chamber. The valves may be programmed to work during certain selected engine conditions to improve the homogeneity of the charge which will thus burn more effectively. For example, tumble is particularly desirable and effective during the first 20 seconds of a cold engine start and also at light engine load conditions (e.g., less than about 3,000 rpm).
Prior art tumble control valves generally comprise a valve body having an internal cavity and a valve flap or blade pivotally disposed within the internal cavity of the valve body. The valve blade pivots between fully open and fully closed positions. When in the fully closed position, the blade lies substantially perpendicular to the longitudinal axis of the valve body. In this position, the bottom edge of the blade lies in close relationship to the bottom wall of the internal cavity, thus effectively sealing off this area to air flow. Conversely, the top edge of the blade lies in spaced relation to the top wall of the internal cavity to define a gap wherethrough air may flow. Thus, in the fully closed position of the valve blade, maximum tumble is generated since the air flow is forced to pass through the gap defined along the top wall of the internal cavity of the valve body. When engine conditions indicate tumble or swirl are not needed, the valve opens to allow air flow through the runner in the normal manner.
The charge motion control valves are typically positioned in each air intake runner in close proximity to the inlet to the engine head port and intake valve. If the valves are located at too great a distance, the tumble or swirl effect is reduced or eliminated before the air intake charge enters the combustion chamber. In some applications, a shelf or flow divider is placed in the runner, just downstream of the charge motion valve, to extend the biased flow closer to the intake valve in the head. Because of the need to have the charge motion control valves close to the intake valve in the head, V6 and V8 applications of tumble and swirl control require two sets of valves, one set for the right bank and one set for the left bank of the engine.
A common actuator is usually employed to drive both sets of motion control valves. An exposed linkage extends from either side of the actuator to drive each of the two sets of valves. This linkage arrangement between the two sets of valves has drawbacks such as wear and breakage of the linkage parts, the added parts cost and space requirements within the engine compartment, for example. Although two shafts and associated linkages to the actuator are not required in a straight, in-line engine, the fact that the tumble control valves must be placed close to the cylinder heads places limitations on engine and manifold design and creates possible valve failure due to the high heat environment in the vicinity of the combustion chambers. It would therefore be desirable to have a design and method for controlling motion control valves of an engine which do not have the above-mentioned drawbacks of present day motion control valve drive arrangements.